Fix gt doctor hanging on large workspaces

Two fixes:

1. FindAllLocks in lock/lock.go was walking into massive git repo
   clones (e.g., 13GB java repos in crew members). Added skipDirs map
   to skip .git, node_modules, vendor, target, build, and other large
   irrelevant directories during filepath.Walk.

2. CloneDivergenceCheck's git fetch could hang indefinitely waiting
   for SSH authentication prompts. Added environment variables to
   disable interactive SSH features:
   - GIT_SSH_COMMAND='ssh -o BatchMode=yes -o ConnectTimeout=3'
   - GIT_TERMINAL_PROMPT=0

Doctor now completes in ~2 minutes instead of hanging indefinitely.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/doctor/branch_check.go

@@ -534,10 +534,16 @@ func (c *CloneDivergenceCheck) getCloneInfo(path string) (cloneInfo, error) {
 
 	// Fetch to make sure we have latest refs (silent, ignore errors)
 	// Use a short timeout to prevent hanging on network issues, SSH prompts, or credential dialogs
+	// Also disable SSH interactive features to prevent blocking on password/passphrase prompts
 	fetchCtx, fetchCancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer fetchCancel()
 	cmd = exec.CommandContext(fetchCtx, "git", "fetch", "--quiet")
 	cmd.Dir = path
+	// Disable SSH password prompts and batch mode - fail fast instead of hanging
+	cmd.Env = append(os.Environ(),
+		"GIT_SSH_COMMAND=ssh -o BatchMode=yes -o ConnectTimeout=3",
+		"GIT_TERMINAL_PROMPT=0",
+	)
 	_ = cmd.Run()
 
 	// Count commits behind origin/main